This invention relates to an internally heated fusing device for use in an electrostatographic copying machine, and more particularly it relates to an internally heated fusing device which has a novel composite thermally conductive layer thereon.
The electrostatographic process for making copies of documents is now well known. For example, one such embodiment, as adopted for an automatic xerographic reproducing machine, is shown in Thettu U.S. Pat. No. 3,988,817. As shown in FIG. 1 of that patent, a number of processing stations are arranged around the periphery of a xerographic plate or surface formed in the shape of a drum. These processing stations include a charging station, an exposure station, a developing station, a transfer station, a drum cleaning and discharge station, and a fusing station. The present invention is concerned with the fusing step in such a reproduction machine. The fusing of toner powder image to a support or sheet by the application of heat and/or pressure is also generally known. Usually, such application of heat and/or pressure is carried out with a pair of rolls called a fuser roll and a pressure roll. The problems encountered by such fusing devices include toner offset, copy quality degradation, and paper curl in the copy sheets, etc. There have been many attempts to deal with these problems by the construction of various fusing devices. Although many of such prior attempts have been successful in producing fine copies, there is a continuing need for improved fusing devices. For example, in a modern reproduction machine, the speed may be one copy per second or even two copies per second. Thus, an internally heated fusing device must have the capability of transferring sufficient heat to the surfaces involved to fuse at such rates.
In Imai U.S. Pat. No. 4,074,001, there is disclosed a fixing roll for electrophotography having a surface layer of a cured room temperature vulcanized silicone rubber composition which is made of a mixture consisting of two diorganopolysiloxanes, a crosslinking agent, a reaction catalyst and three kinds of inorganic fillers with no siliceous fillers.
In Takiguchi et al U.S. Pat. No. 4,064,313, there is disclosed a fuser member having a coating of silicone rubber thereon. The coating of silicone rubber is adhered to the base member by means of a polysiloxane composition.
In Stewart U.S. Pat. No. 4,011,362, there is disclosed metal substrates, including fuser rolls, which are coated with carboxy functional siloxanes to improve release characteristics.
In Thettu U.S. Pat. No. 3,988,817, there is disclosed a fuser roll which is made of an elastic compressible coating of a silicone rubber on a rotating member. This patent also discloses a pressure roll which is made of an elastomeric core of a silicone rubber, a rigid but flexible sleeve on the core, and an outer coating of an elastomeric silicone rubber.
Finally, in Thettu et al U.S. Pat. No. 3,849,062, there is disclosed a fusing member which is made of a rotating member having an elastic compressible coating of a silicone rubber thereon. The elastic compressible coating of silicone rubber of this patent is reinforced by a reinforcing jacket to impart structural strength to the fuser roll coating.
In view of the foregoing, it is an object of the present invention to provide an improved fuser roll for use in an electrostatographic copying machine.
It is another object of the present invention to provide an improved fuser roll which has outstanding heat transfer properties as well as possessing excellent release characteristics.
These and other objects of the invention can be gathered from the following disclosure.